A swab is impregnated with a test reagent such that a test for a specific substance can be effected by rubbing the impregnated swab over the surface to be tested and then viewing the swab for a reagent reaction. A method for testing for a metal includes impregnating a swab with a reagent, such as, for...http://www.google.co.uk/patents/US5039618?utm_source=gb-gplus-sharePatent US5039618 - Test swab cartridge type device and method for detecting lead and cadmium
